The present invention relates to the field of chemical dispensing systems, and more particularly to such systems in which a number of liquid chemicals are dispensed selectively from chemical reservoir pods to a number of washing machines according to wash formula requirements.
Commercial and institutional laundry facilities typically employ a plurality of washing machines in an automated system including a plurality of laundry chemical supply stations. The system has a controller which has in memory, or is supplied via an input device a formula for each type of load to be washed. The formula determines the quantity of each laundry chemical, for example detergent, bleach, water treatment, fabric softener, etc., as well as the operating times for each washing cycle. In addition to control of the quantity of each chemical, the formula specifies that the chemicals must be injected in a prescribed sequence and at the proper time for best results. Since commercial and institutional laundries are likely to use relatively large quantities of several chemicals, the accuracy of the quantity delivered is critical both to the quality of the washing results and to the operational efficiency of the laundry plant.
A known system for commercial washing operations is taught in U.S. Pat. No. 5,590,686 to Prendergast, entitled Liquid Delivery Systems. The Prendergast patent teaches the use of a flowmeter to control the amount each chemical that is delivered from its chemical reservoir to the washing machine. The flowmeter is connected to the discharge end of a chemical supply piping system so that chemical flow from any of several chemical reservoirs passes through the flowmeter. The major drawback to the Prendergast device is that a flowmeter is known to have limited accuracy, and in a commercial or institutional laundry system, accurate control of the quantity of each chemical is important. By its nature, a flowmeter is designed and calibrated to measure a liquid of a particular viscosity and at a particular rate of flow. Since there is a single flowmeter in a system dealing with a plurality of chemicals, and since the chemicals generally will have differing viscosities, the amount of any one or several of the chemicals will not be accurately measured. A further drawback of a chemical delivery system that uses a flowmeter to measure chemical delivery quantity is that if the amount of a particular chemical in a reservoir is less than the amount called for by the formula, there is no means to signal an insufficiency before the chemical supply is totally depleted. In this case, either the laundry batch will run with one or more chemicals at lower than the specified quantity or the process will have to be stopped to wait for chemical replenishment.
Therefore, it is an object of the present invention to provide a chemical delivery system capable of achieving accurate control of the quantity of each of a plurality of chemicals from individual sources.
It is an additional object of the invention to verify that sufficient chemical is available for a next wash cycle to run.
These and other objects of the present invention will become apparent through the disclosure of the invention to follow.
The invention provides a system for automatically dispensing a defined volume of one or more chemicals for use in one or more washing machines. Each chemical is stored in a reservoir pod having a chemical pressure sensor connected adjacent its bottom, a chemical output valve connected into an output pipe, and an overflow sensing switch connected adjacent its top. A single output pump is connected by supply piping between a water supply tank and the washing machines, with each chemical output valve connected to the piping. A diverter valve connects each washing machine with the supply piping. An output pressure sensor is connected between each diverter valve and its respective washing machine.
When a washing cycle is started, a controller requests a selected quantity of each required chemical according to a formula. The controller, through each chemical pressure sensor, verifies that sufficient quantity of each required chemical is available. If insufficient quantity is available, the cycle is suspended until the chemical supply is replenished by activation of a chemical refill pump to refill the deficient pod. If sufficient quantity is available, the single output pump is activated to draw water through the piping, and a diverter valve is set to channel the water to the requesting washing machine, with the output pressure sensor verifying that water is flowing. After a selected quantity of water has entered the washing machine, a first chemical output valve is opened and the chemical flows into the water flow in the piping. The chemical pressure sensor for the pod being accessed sends continuous pressure data to the controller which determines when the selected volume of chemical has been supplied and shuts the chemical output valve. Additional chemicals from other pods are added as required.
The system also includes calibration routines for the pressure sensors and a test routine for verification that power and water are available and the pumps and valves operate properly. A modified system is adapted for use in the supply of chemicals to xe2x80x9ctunnelxe2x80x9d type-washing equipment.